National Geographic's Restless Earth Collection
Asteroids Deadly Impact Volcano Nature's Fury. The devastating powers of earthquakes, hurricanes, tornadoes, volcanoes and other earth-shattering forces of nature in dramatic scenes of destruction and inspiring human courage captured by the acclaimed filmmakers of National Geographic
 Basalt lava (glowing rock) oozes over basalt lava flow |
Basalt Basalt is a hard, black volcanic rock with less than about 52 weight percent silica (SiO 2 ). Because of basalt's low silica content, it has a low viscosity (resistance to flow). Therefore, basaltic lava can flow quickly and easily move >20 km from a vent. The low viscosity typically allows volcanic gases to escape without generating enormous eruption columns. Basaltic lava fountains and fissure eruptions, however, still form explosive fountains hundreds of meters tall. Common minerals in basalt include olivine, pyroxene, and plagioclase. Basalt is erupted at temperatures between 1100 to 1250° C. |
NOVA - In the Path of a Killer Volcano
The scientists who remain behind- and see some astonishing footage of the world's largest volcanic eruption in 80 years. Local tribes people were the first to see the signs. "There was a flash of light from the sky,"